Benchmark: JavaScript spread operator vs Object.assign (to empty object) performance

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36

Browser/OS: Chrome 70 on Mac OS X 10.14.1

View result in a separate tab

Test name	Executions per second
Using the spread operator	5225229.5 Ops/sec
Using Object.assign	4654577.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this JavaScript microbenchmark.

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches: using the spread operator (`...`) and `Object.assign` (with an empty object) for merging objects.

**Options Compared**

Two options are compared:

1. **Using the spread operator**: This involves using the spread operator (`...`) to merge two objects into a new one.
2. **Using `Object.assign` with an empty object**: This involves using the `Object.assign()` method to merge two objects, passing an empty object as the first argument.

**Pros and Cons of Each Approach**

* **Using the spread operator**:
	+ Pros: concise, readable syntax, can be more efficient for small objects.
	+ Cons: may not be supported in older browsers or environments that don't support ES6+ features.
* **Using `Object.assign` with an empty object**:
	+ Pros: widely supported across all browsers and environments, avoids potential issues with newer language features.
	+ Cons: requires more code and may look less concise.

**Library Used**

There is no library explicitly mentioned in the benchmark definition or test cases. However, it's likely that a standard JavaScript implementation (e.g., V8) is used to execute the benchmarks.

**Special JS Feature/Syntax**

The benchmark uses the spread operator (`...`), which is a syntax introduced in ES6+ languages (including modern JavaScript). This feature allows for concise and expressive way of merging objects. However, as mentioned earlier, this may not be supported in older browsers or environments that don't support ES6+ features.

**Other Alternatives**

In the past, developers might have used other approaches to merge objects, such as:

* Using the `concat()` method: `const finalObject = { ...firstObject }.concat(secondObject);`
* Using a loop: `const finalObject = {}; for (const key in secondObject) { finalObject[key] = secondObject[key]; }`

However, these approaches are generally less efficient and less concise than using the spread operator or `Object.assign`.

**Benchmark Preparation Code**

The benchmark preparation code is empty, which means that the test cases assume that the required objects (`firstObject` and `secondObject`) are already defined and available for use.

Related benchmarks:

JavaScript spread operator vs Object.assign (to empty object) performance (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign

Created: 6 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):